The present invention relates to a method for sterilizing conduits that convey fluid to medical instruments, especially dental instruments.
It is known that the heart of any piece of dental apparatus or equipment is the water and air system. In the system, the water line supplies fluids used by dental equipment and patients (water or physiological saline for tumblers and handpieces), or consumer units (swilling water for the spittoon), while the air line is used for certain items of equipment (air spray handpieces, cooling air and driving air).
With increases in general standards of hygiene and in the xe2x80x9cfragilityxe2x80x9d of dental apparatus and equipment, several advances have been made in the design and function of the fluid systems of dental units not only to guarantee their efficient operation and durability but also to maintain the sterility of the conduits both during and after successive patient treatments. Considering that the basic structure of such fluid systems comprises a first main line supplying water from the mains, and a second main line supplying air from an external source (compressor), each of which has a plurality of branches serving the water- or air-using devices, different systems have been designed on the basis of different methods aimed at improving the functioning and disinfection of these fluid lines or parts of them.
In particular, the present specification focuses attention on the water line which is disinfected according to two different methods, one using a continuous cycle and the other a discontinuous cycle, and requiring additional devices to be fitted to the basic structure of the system: in U.S. Pat. Nos. DE-3.028.550 and DE-3.611.329, the problem is addressed using equipment comprising a tank of disinfectant connected to a unit for dosing the disinfectant into the conduits that convey the fluid to the devices of the dental unit, in such a way as to supply the water line with disinfected water according to the amount of water required by the devices themselves.
On the other hand, in the solutions based on the discontinuous disinfection/sterilization cycle, as disclosed in patent publications EP-111.249 and EP-317.521 (the latter being by the present Applicant), the mains water supply is shut off, and a dedicated branch equipped with an independent tank is used to feed sterilizing liquid into the conduits that supply water to the handpieces. After a preset time, depending on the quality of disinfection/sterilization required and the properties of the sterilizing liquid, the line is opened again and the sterilizing liquid drained out.
The drainage of the sterilizing liquid is performed by flushing water supplied by the main line and opening the control valves on the handpieces so that the water rinses the water line and flows out into an appropriate drain.
This method, which has been used on dental units for some time, has proved to be very effective and practical. However, the Applicant, always seeking to improve the sterilization and post-sterilization steps of dental units, has made significant changes to the sterilization method in an attempt to make it safer still, in particular by improving the disinfection level of the step of draining the sterilizing liquid out of the line. This is because it has been found that the flow of non-sterile water from the main water source makes it impossible to maintain the sterility of the conduits, thus partly offsetting the sanitizing effect of the sterilizing liquid.
This sterilization parameter is very important when it is necessary to use physiological saline for a treatment on a patient. In such a case, the saline is conveyed along conduits that are not completely sterile, thus greatly diminishing the effect of the sterilizing cycle previously carried out.
The aim of the present invention, therefore, is to maintain the conduits of the dental unit water lines at the highest possible level of sterility.
Accordingly, the invention, as disclosed in the claims below, provides a method for sterilizing the conduits that convey fluid to medical instruments, especially dental handpieces and comprising the following steps: removing at least the end portions of supply branches or forks of the handpieces from their respective rest positions and placing them in a container; introducing a sterilizing liquid in each of the supply branches or forks for a predetermined time; and draining the sterilizing liquid out of the branches or forks; the final draining step is effected by flushing the branches or forks with a sterile fluid that can be supplied through a second branch independent of the main water source.